England · Particle model of matter · Unit PM-U2

Internal energy and state changes

A proposed unit with 2 lectures, independent practice and a unit assessment.

Unit scope

Filters show lectures with relevant core content. Mixed lectures retain clearly labelled Higher/separate extensions; those extensions are not required on other routes. Difficulty is a design rating, not a GCSE grade.

Lectures

PM-U2 · Internal energy and state changes

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PM-03 · PM-U2 · Planned

Internal energy, temperature and heating

  • ScopeShared
  • Difficulty2 / 4 · proposed
  • Time25–30 min · estimated
  • StatusPlanned

Learning objectives

Distinguish internal energy and temperature; relate heating to kinetic/potential particle energy changes.

8463 §§4.3.2.1–4.3.2.2 / 8464 §§6.3.2.1–6.3.2.2

DfE single-science pp.42–43 / Combined pp.35. Evidence checked 30 September–1 October 2026. Skills: WS1.2,3.6; MS3b,3c.

Needs firstEN-08,PM-01

Explanation

Internal energy includes the kinetic and potential energies of all particles. Temperature relates to particle motion but does not measure the total internal energy of a sample. Equal temperature does not imply equal energy when masses or materials differ.

Concepts, equations and units: Internal energy=sum particle kinetic and potential energies; ΔE=mcΔθ for temperature change without phase change; J,kg,J/(kg °C),°C.

Prediction, demonstration and game exercise

Predict, observe, explain

Compare samples at equal temperature but different mass; interpret particle animation as a model.

Planned learner game exercise

Give equal thermal inputs to selectable samples; predict temperature change then annotate particle changes.

Independent practice

Two ΔE calculations and an explanation of equal temperature/different internal energy.

Original practice example · Shared

Two samples of the same material are at the same temperature, but one has twice the mass. Must their internal energies be equal?

Show working and model answer

Working / reasoning

No: temperature is not total internal energy, and the larger sample contains more particles under comparable conditions.

Answer

No; the larger sample has a greater total internal energy under the stated comparable conditions.

Exit check and success criteria

Both calculations correct and internal energy includes both particle contributions.

During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.

Misconceptions, practical links and mastery

Check these misconceptions

Temperature measures total energy; heat is contained as a substance; particles get bigger when heated.

Practical preparation

RP-P1/RP-C14 conceptual revisit; no additional RP.

Virtual preparation and revision only. Required hands-on activities and school records remain separate.

Proposed mastery

0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.

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PM-04 · PM-U2 · Planned

Changes of state and latent heat

  • ScopeShared
  • Difficulty3 / 4 · proposed
  • Time30–35 min · estimated
  • StatusPlanned

Learning objectives

Explain reversible state changes and mass conservation; calculate latent energy; interpret heating/cooling plateaux.

8463 §§4.3.1.2,4.3.2.3 / 8464 §§6.3.1.2,6.3.2.3

DfE single-science pp.42–43 / Combined pp.35. Evidence checked 30 September–1 October 2026. Skills: WS1.2,3.5; MS3c,3d,4a.

Needs firstPM-03

Explanation

During a state change, energy changes particle separation/interaction potential energy while temperature can remain constant. Specific latent heat is energy per kilogram for that change. In ordinary reversible state changes, total mass is conserved.

Concepts, equations and units: E=mL; J,kg,L in J/kg; latent fusion/vaporisation; constant-temperature phase change at stated pressure.

Prediction, demonstration and game exercise

Predict, observe, explain

Heat a fixed mass through melting and boiling; reveal energy input with constant-temperature intervals.

Planned learner game exercise

Allocate energy to a sample across states; label solid, liquid, gas and mixed-phase intervals.

Independent practice

Three latent-heat calculations and a temperature–time graph explanation, including cooling.

Original practice example · Shared

Melt 0.20 kg of a solid with latent heat 100,000 J/kg at its melting point. Find energy required.

Show working and model answer

Working / reasoning

E = mL = 0.20 × 100,000.

Answer

20,000 J.

Exit check and success criteria

Two values correct, plateau linked to potential-energy change and mass conserved.

During practice, compare the prediction with evidence and give an error-specific prompt. The exit item uses a fresh context or fresh values, answered independently.

Misconceptions, practical links and mastery

Check these misconceptions

Temperature always rises when heating; particles vanish on evaporation; latent heat means no energy transfer.

Practical preparation

Optional teacher-supervised heating/cooling demonstration; not an RP.

Virtual preparation and revision only. Required hands-on activities and school records remain separate.

Proposed mastery

0: not yet evidenced. 1: supported. 2: independent exit criteria met. 3: successful changed-context transfer. Advance at 2; revisit with fresh retrieval. These are not GCSE grades.

Full lecture page →

Area capstone

Sources and full programme

Sources checked 30 September–1 October 2026. Specifications govern content; textbooks supplement it. England has no single prescribed Physics course book. The full planning document includes sourced comparisons of Collins separate Physics and Trilogy books, Hodder/Hachette Physics and Oxford Physics listings, with access/approval limitations.

Download the complete Markdown programme and coverage matrix

A subsection map is proposed coverage. Clause-level educator review, item moderation, model validation and hands-on provision remain release gates. No all-board alignment or exam-board endorsement is claimed.